In an optical communication system, it is generally necessary to couple an optical fiber to an opto-electronic transmitter, receiver or transceiver device and, in turn, to couple the device to an electronic system such as a switching system or processing system. These connections can be facilitated by modularizing the transmitter, receiver or transceiver device. An opto-electronic transceiver module commonly includes an opto-electronic light source, such as a laser, and an opto-electronic light receiver, such as a photodiode, and may also include various electronic circuitry associated with the laser and photodiode. For example, driver circuitry can be included for driving the laser in response to electronic signals received from the electronic system. Likewise, receiver circuitry can be included for processing the signals produced by the photodiode and providing output signals to the electronic system. Optics such as lenses and reflectors may also be included. In an opto-electronic transceiver module, the foregoing opto-electronic, electronic and optical elements are enclosed within a housing. The housing can have, for example, the elongated, rectangular shape associated with the standard configuration commonly referred to in the art as Small Form Factor (SFF) or Small Form Factor Pluggable (SFP).
The opto-electronic transceiver module housing typically includes one or more optical ports into which the connector end of an optical fiber cable can be plugged. The connector at the end of such an optical fiber cable can have, for example, a form commonly referred to in the art as LC (originally an abbreviation for Lucent Connector). An LC connector has a generally square profile, with the end of an optical fiber held in a ferrule at its center. An LC connector can be plugged into an optical port in the transceiver module. Each optical port of such a transceiver module is defined by an opening in the transceiver module housing having a generally square profile corresponding to that of the LC connector. The optical port is further defined by an end of an electro-optical assembly that extends from within the housing into the optical port opening of the housing. The end of the electro-optical assembly that extends into the optical port opening of the housing may be referred to as a ferrule end because it receives the ferrule of the LC connector when the LC connector is plugged into the optical port. Note that in an opto-electronic transceiver module there are two of the above-described optical ports: one for a transmit path and one for a receive path. An LC connector having a transmit portion and a receive portion is sometimes referred to as a duplex LC connector.
It is important that the ferrule end of the electro-optical assembly is precisely aligned with the walls of the optical port opening or openings into which the ferrule end extends, so that when a standard LC connector is plugged into the optical port, the end of the optical fiber is precisely optically aligned with the optical path through the electro-optical assembly. The degree of precision, i.e., tolerances between various reference points in the optical port, may be defined by well-known standards such as the Fiber Optic Connector Intermateability Standard (FOCIS). Such standards and other means (e.g., multi-source agreements or MSAs) help ensure that opto-electronic transceiver modules manufactured by various parties are inter-operable with LC connectors or other optical connectors manufactured by various other parties.
One common method of aligning the ferrule end of the electro-optical assembly with the interior walls of the optical port opening involves using an alignment jig. An alignment jig for a transceiver module has two posts, each with a shape or profile corresponding to that of a single LC connector. To align the ferrule end of the electro-optical assembly with the interior walls of the optical port opening, the posts of the alignment jig are inserted into the optical port openings in the module housing. The posts mate with the ferrule ends of the electro-optical assembly and hold the ferrule ends in fixed relation to the optical port openings in the module housing. While the jig is in place, epoxy that is applied between other portions of the electro-optical assembly (e.g., the printed circuit board) and other portions of the module housing is cured by placing the module and alignment jig together in a curing oven. The curing process can take a substantial amount of time, such as an hour or more. In addition, in a typical manufacturing operation, the process is performed on many modules in parallel, requiring that many alignment jigs be provided in parallel. The need for a large number of alignment jigs and an hour or more of curing time contribute to inefficiency in the alignment step of the manufacturing process.